Finite Element Method Magnetics

Figure 2.33: Block Property dialog.material that is being described. Enter it in the Name edit box in lieu of “New Material.”Next, permittivity for the material needs to be specified. BELA allows you to specify differentrelative permittivities in the vertical and horizontal directions (ε x for the x- or horizontal direction,and ε y for the y- or vertical .A volume charge density (ρ) can also be prescribed by filling in the appropriate box in thematerial properties dialog.Materials LibrarySince one kind of material might be needed in several different models, FEMM has a built-in libraryof electrostatic Block Property definitions. The user can access and maintain this librarythrough the Properties | Materials Library selection off of the main menu. When this optionis selected, the Materials Library dialog pictured in Figure 2.34 appears.This dialog allow the user to exchange Block Property definitions between the current modeland the materials library via a drag-and-drop interface.A number of different options are available via a mouse button right-click when the cursor islocated on top of a material or folder. Materials can be edited by double-clicking on the desiredmaterial.Material from other material libraries or models can be imported by selecting the “ImportMaterials” option from the right-button menu that appears when the pointer is over the root-levelfolder of either the Library or Model materials lists.The materials library should be located in the same directory as the femm executable files,under the filename statlib.dat. If you move the materials library, femm will not be able to findit.Conductor PropertiesThe purpose of the conductor properties is mainly to allow the user to apply constraints on thetotal amount of charge carried on a conductor. Alternatively, conductors with a fixed voltage can53